She can be a Clingy Jealous Girl toward Mamoru and hates when other women get close to him, but she is not always faithful herself, judging by the way she stares at other boys. Apparently, only one of them needs to be 100% devoted. This is mostly in the first anime.
In one episode, she slaps Mamoru for forgetting her birthday even though she never told him, but she doesn't know his birthday either.
She accuses Usagi of being "ungrateful" for rejecting her mother's hot cakes (and she only rejected them because she had already eaten something and didn't even know her mother was making something for her in the first place) when she herself does not appreciate that Usagi has constantly put her own life on the line to save her from danger.
In one episode, she gets viciously angry at Usagi after the latter unknowingly steals the pie she baked for a classmate. In other episodes, she would knowingly steal Usagi's food just for the sake of it.
She (along with the others) criticizes Usagi for her laziness, even though she is shown to be rather lazy herself; for instance, she has Usagi carry all the groceries while she herself is empty-handed.
Luna the Cat also has her moments:
She gets on Usagi's case when the latter allegedly wet the bed, but she doesn't hold it against Chibi-Usa when it's revealed it was her who did it. When Usagi points this out to Luna, Luna excuses herself by telling her, "Well, you deserved it."
When she merely thinks Diana is the lovechild of Artemis and another cat, she violently rages at him. Fast-forward to Sailor Stars, where she openly fawns over Yaten, perfectly fine with the fact that Artemis knows.
She also had the nerve to taunt Usagi for not noticing if Chibi-Chibi was her daughter or not when she herself failed to realize that Diana was her daughter and jumped to conclusions. Usagi rightfully calls her out on this, and she quickly becomes embarrassed.
She usually does nothing to stop Chibi-Usa from antagonizing Usagi, yet she has the nerve to call out Usagi whenever she retaliates in any way.
Haruka Tenoh is another example:
During the early stages of her relationship with Michiru, Haruka snarked that she didn't think a privileged rich girl like her could possibly understand a concept as bleak as the apocalypse, even though Haruka herself is a privileged rich girl.
Before going to confront Eudial with Michiru, Haruka tells Usagi that they won't let her slow them down with her "half-baked play war". She says this, even though she and Michiru didn't have a concrete plan for finding the Talismans all season and they hadn't formed a plan for when they confronted Eudial and when they did, she quickly gained the upper hand. Had Usagi heeded their threat and stayed away, Haruka and Michiru would've died and the Death Busters would've gotten a hold on two Talismans.
Both her and Michiru often display Ignorant of Their Own Ignorance when it comes to criticizing the Inner Guardians. Generally, this takes the form of treating the Inner scouts as new girls who haven't had to make tough sacrifices. The truth being Venus had been active for at least a year prior to the events of season 1 (and Michiru being active at most around season 2), and all five of them dying in heroic sacrifices in the end of Season 1.
Rei often scolds and mocks Usagi for certain traits and habits, yet she herself exhibits the exact same behavior or does it after scolding Usagi for doing so. One of the best examples of this is in the fifth season, when Usagi is shown worrying about Seiya, at which point Rei shows up and says, "Stop worrying about someone else and go study!" Ignoring that Rei is, at that moment, worrying about someone else and not studying.
